The present invention relates to a device for controlling the working conditions of a self-propelled vehicle such as an agricultural tractor.
As is known, self-propelled vehicles, particularly hybrid types, are equipped with a single pedal-, lever- or pedal-and-lever-operated device for regulating the travelling speed of the vehicle according to the set gear ratio.
In the case of a diesel internal combustion engine, in particular, fuel injection can be governed to obtain the best conditions in terms of specific consumption, noise level, etc.
All this, however, fails to take into account connection of the PTO, the device by which the vehicle supplies power externally by means of a rotary shaft. When connecting the PTO, in fact, the operator must also select its rotation speed, which is normally set to 540, 750 or 1000 rpm, depending on the type and size of the implement attached to the PTO.
Consequently, since the PTO is connected mechanically to the output shaft of the internal combustion engine, a variation in the rotation speed of the drive shaft to adapt it to the best PTO conditions also results in a variation in the travelling speed of the vehicle, which is obviously undesirable.
By way of an inventive solution, it is therefore proposed to separate the speed of the vehicle from that of the drive shaft connected directly to the PTO, which of course calls for a power unit permitting internal gear ratio adjustment to separate the speed of the internal combustion engine from that of the vehicle, and so obtain both the required PTO and vehicle speeds.
In this case, the system continues to provide the required vehicle travelling speed, but at the expense of minimum consumption, low noise, etc.
It is an object of the present invention to provide a device for controlling the working conditions of a self-propelled vehicle, as defined in the accompanying Claims.
It is an advantage of this invention that the mechanical power is divided into two streams.
It is a feature of this invention that the first mechanical stream is converted into an electric stream which is manipulated according to the required working conditions of the power unit.
It is another feature of this invention that the electric power is converted back to mechanical and is combined with the second mechanical stream which has been conditioned for balance by, so as to mate with, the first stream.
It is another object of this invention to provide for direct control of the speed of engine when the PTO is connected, with precedence over electronic control of the speed of the vehicle.
It is another advantage of this invention that in an underpower situation the vehicle would have to travel at a lower speed than the device setting until a balance is reached between the total power transmitted and the power supplied by the engine.
These and other objects, features and advantages are accomplished according to the instant invention by providing a device controlling the operating conditions of a self-propelled vehicle. The device includes a first device for controlling the travelling speed of the self-propelled vehicle, and a second device for controlling the output speed of an internal combustion engine. The first and second devices are separate from each other.